Silver halide solution physical developing solution

ABSTRACT

A black-and-white silver halide developing solution and a silver halide solution physical developing solution are used in sequence to provide electrically-conductive film elements from conductive film element precursors that contain photosensitive silver halide emulsions on one or both supporting sides of a transparent substrate. The two developing solutions have unique combinations of developing agents and other essential components to provide complete development of imagewise exposed silver halide to form highly electrically-conductive silver metal in predetermined patterns.

RELATED APPLICATIONS

Reference is made to the following copending and commonly assignedpatent applications, the disclosures of all of which are incorporatedherein in their entirety:

U.S. Ser. No. 13/919,203 filed Jun. 17, 2013 by Gogle, Lowe, O+Toole,and Youngblood;

U.S. Ser. No. 14/166,910 filed Jan. 29, 2014 by Lushington;

U.S. Ser. No. 14/265,418 filed Apr. 30, 2014 by Lushington;

U.S. Serial No. 14/______ filed on even date herewith by Youngblood andLowe and entitled “Method for Providing Conductive Silver Film Elements”(Docket K001739/JLT); and

U.S. Serial No. 14/______ filed on even date herewith by Youngblood andLowe and entitled “Silver Halide Developing Solution” (DocketK001774/JLT).

FIELD OF THE INVENTION

This invention relates to a unique silver halide solution physicaldeveloping solution useful in a method for providing electricallyconductive silver film elements. Such electrically-conductive silverfilm elements can be provided with predetermined patterns ofelectrically-conductive silver and used in various electronic devices orthey can be further processed to provide patterns of otherelectrically-conductive metals.

BACKGROUND OF THE INVENTION

Rapid advances are occurring in various electronic devices especiallydisplay devices that are used for various communication, financial,capture, and archival purposes. For such uses as touch screen panels,electrochromic devices, light emitting diodes, field effect transistors,and liquid crystal displays, electrically-conductive films are essentialand considerable efforts are being made in the industry to improve theproperties of those electrically-conductive films as well as methods formaking them.

In addition, as the noted display devices have developed in recentyears, their attraction has increased greatly with the use of touchscreen technology whereby light touches on the screen surface with afinger or stylus can create signals to cause changes in screen views orcause the reception or sending of information, telecommunications,interaction with the Internet, and many other features that are beingdeveloped at an ever-increasing pace of innovation. Touch screentechnology has been made possible largely by the use of transparentelectrically-conductive grids on the primary display so that thelocation of the noted touch on the screen surface can be detected byappropriate electrical circuitry and software.

Currently, most touch screen displays use Indium Tin Oxide (ITO)coatings to create arrays of capacitive areas used to distinguishmultiple point contacts. ITO coatings have significant disadvantages.Indium is an expensive rare earth metal and is available in limitedsupply from very few sources in the world. ITO conductivity isrelatively low and requires short line lengths to achieve adequateresponse rates. Touch screens for large displays are broken up intosmaller segments to reduce the conductive line length to an acceptableresistance. ITO is a ceramic material, is not readily bent or flexed,and requires vacuum deposition with high processing temperatures toprepare the electrically-conductive layers.

Silver is an ideal conductor having conductivity 50 to 100 times greaterthan ITO. Silver is used in many commercial applications and isavailable from numerous sources. It is highly desirable to makeelectrically-conductive film elements using silver as the source ofconductivity, but it requires considerable development or otherprocessing operations to obtain the optimal electrically-conductiveproperties.

U.S. Patent Application Publication 2011/0308846 (Ichiki) describes thepreparation of electrically-conductive films formed by reducing a silverhalide image in electrically-conductive networks with silver wire sizesless than 10 μm, which electrically-conductive films can be used to formtouch panels in displays.

In addition, U.S. Pat. No. 3,464,822 (Blake) describes the use of asilver halide emulsion in a photographic element to form anelectrically-conductive silver surface image by development and one ormore treatment baths after development.

U.S. Pat. No. 7,829,270 (Nakahira) describes the use of photosensitivesilver halide materials to form electrically-conductive silver metalpatterns. After exposure of the photosensitive silver halide materials,they are processed using a black-and-white development solution followedby fixing and physical development and electroless plating operations.

Moreover, U.S. Pat. No. 8,012,676 (Yoshiki et al.) also describessimilar processes but further including operations to enhance electricalconductivity of the resulting silver metal images.

Thus, it is known to provide electrically-conductive silver patterns ontransparent films using various processing solutions and conditions.However, there is a further need to improve the electrical conductivityof silver patterns, especially silver patterns in the form of fine lineswithout increasing D_(min). That is, there is a need to balance improvedsilver metal conductivity, increased transparency, and low D_(min) inelectrically-conductive silver images. It with these needs in mind, thatthe present invention was discovered.

SUMMARY OF THE INVENTION

The present invention provides a silver halide solution physicaldeveloping solution comprising:

(a) a primary developing agent that is a hydroquinone or ascorbic acidor derivative of either, in an amount of at least 0.01 mol/l and up toand including 1 mol/l, and

(c) a silver halide dissolution catalyst in an amount of at least 0.001mol/l and up to and including 0.1 mol/l, and

the silver halide solution physical developing solution containingsubstantially no (b) catalytic developing agent.

The present invention provides several advantages with improvedconductive film elements containing highly electrically-conductivesilver metal images that can be arranged in predetermined patterns offine lines or grids. The resulting conductive film elements exhibit highconductivity and high transparency while keeping the (visual) D_(min) aslow as possible, for example, less than or equal to 0.3 after processingin a fixing solution. These advantages are achieved by using a uniquecombination of black-and-white silver halide developing solutions beforefixing including the silver halide solution physical developing solutionof this invention.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to various embodiments of thepresent invention and while some embodiments can be particularlydesirable for specific uses, the disclosed embodiments should not beinterpreted or otherwise considered to limit the scope of the presentinvention, as claimed below. In addition, one skilled in the art willunderstand that the following disclosure has broader application than isexplicitly described and the discussion of any embodiment is notintended to limit the scope of the present invention.

DEFINITIONS

As used herein to define various components of the processing solutionsand various layers and formulations used to prepare the conductive filmelement precursors, unless otherwise indicated, the singular forms “a,”“an,” and “the” are intended to include one or more of the components(that is, including plurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the termdefinition should be taken from an English or chemical dictionary.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are considered to beapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about”. In this manner,slight variations above and below the stated ranges can be used toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values.

Unless otherwise indicated, the term “weight %” refers to the amount ofa component or material based on the total solids of a composition,formulation, solution, or the % of the dry weight of a layer. Unlessotherwise indicated, the percentages can be the same for either a drylayer or pattern, or for the total solids of the formulation orcomposition used to make that layer or pattern.

Unless otherwise indicated, the term “mol %” refers to the molar amountsof a particular component (or mixture of the same class of components)within a solution or dispersion.

A “conductive film element precursor” (or “precursor”) is meant to referto an article or element used in the practice of this invention toprovide the conductive film element of the present invention. Suchconductive film element precursor therefore comprise a precursor to thesilver metal particles, such as a silver halide as described below thatis suitably converted (for example by reduction) to silver metal. Muchof the discussion about the conductive film element precursors isequally applicable to the conductive film elements as most of thecomponents and structure are not changed when silver cations in a silverhalide are converted to silver metal particles. Thus, unless otherwiseindicated, the discussion of substrates, hydrophilic binders andcolloids, and any other addenda in silver halide layers and hydrophilicovercoats for the conductive film element precursors are also intendedto describe the components of the resulting conductive film elements.

Unless otherwise indicated, the terms “conductive film element,”“electrically-conductive film element,” and “electrically-conductivearticle” are intended to mean the same thing. They refer to thematerials containing a hydrophilic layer comprising conductive silvermetal image disposed on one or both supporting sides of a suitablesubstrate. Other components of the article or conductive film elementare described below.

The term “first” refers to the layers on one supporting side of thesubstrate and the term “second” refers to the layers on the opposing(opposite) supporting side of the substrate. Each supporting side of thesubstrate can be equally useful and the term “first” does notnecessarily mean that that side is the primary or better supporting sideof the support.

The term “duplex” is used herein in reference to conductive film elementprecursors and conductive film elements having the described layers onboth supporting sides of the substrate. Unless otherwise indicatedherein, the relationships and compositions of the various layers can bethe same or different on both supporting sides of the substrate.Moreover, the silver halides disposed on the opposing supporting sidesof the substrate can be imaged and processed using the same or differentprocessing solutions and conditions.

ESD refers to “equivalent spherical diameter” and is a term used in thephotographic art to define the size of particles such as silver halidegrains. Particle size of silver halide grains as expressed in grain ESDcan be readily determined using disc centrifuge instrumentation.

Unless otherwise indicated, “black-and-white” refers to silver-formingblack-and-white materials and formulations, and not chromogenicblack-and-white materials and formulations.

Uses

The conductive film element precursors can be used in the practice thisinvention to form conductive film elements comprising aelectrically-conductive silver metal pattern on one or both supportingsides of a suitable substrate. These conductive film elements can beused as devices themselves or they can be used as components in deviceshaving a variety of applications including but not limited to,electronic, optical, sensory, and diagnostic uses. More details of suchuses are provided below. In particular, it is desired to use theconductive film element precursors to provide highly conductive silvermetal patterns comprising lines having a line resolution (line width) ofless than 50 μm, or less than 15 μm, or even less than 10 μm and as lowas 1 μm.

It is particularly useful to prepare conductive film elements comprisingelectrically-conductive silver patterns on first and opposing secondsupporting sides of a transparent substrate.

Such electronic and optical devices and components include but are notlimited to, radio frequency tags (RFID), sensors, touch screen displays,and memory and back panels for displays.

Conductive Film Element Precursors

The conductive film element precursors useful in the practice of thisinvention are photosensitive but do not contain chemistry sufficient toprovide color photographic images. Thus, these precursors are consideredto be black-and-white photosensitive materials forming metallic silverimages following exposure and processing, and are “non-colorimage-forming”.

The conductive film element precursors and the resulting conductive filmelements, including the transparent substrate and all accompanyinglayers on one or both supporting sides, are considered transparentmeaning that the integrated transmittance over the noted visible regionof the electromagnetic spectrum (for example from 410 nm to 700 nm)through the entire element can be 70% or more, or more likely at least85% or even 90% or more. Integrated transmittance can be determinedusing a spectrophotometer and known procedures.

Conductive film element precursors having the same or differentessential layers on both supporting sides of the transparent substratecan be known as “duplex” or “two-sided” conductive film elementprecursors.

The conductive film element precursor can be formed by providing a firstnon-color (that is, silver metal image-forming black-and-white)hydrophilic photosensitive layer on at least one supporting or planarside (as opposed to non-supporting edges) of a suitable transparentsubstrate in a suitable manner. This first non-color hydrophilicphotosensitive layer comprises a silver halide, or a mixture of silverhalides, at a total silver coverage of at least 2500 mg Ag/m², or atleast 3500 mg Ag/m² and in many embodiments less than 5000 mg Ag/m², forexample up to and including 4900 mg Ag/m². However, higher silvercoverage can be used if desired. Thus, this non-color hydrophilicphotosensitive layer has sufficient silver halide intrinsic or addedspectral sensitization to be photosensitive to selected imagingirradiation (described below). The photosensitive layers can be the sameor different in composition and spectral sensitization on the opposingsupporting sides of the transparent substrate.

The one or more silver halides are dispersed within one or more suitablehydrophilic binders or colloids as described below also.

Such conductive film element precursors are therefore treated (imagewiseexposed) in a manner as to convert the silver cations (such as byreduction) into silver metal particles, and this exposed precursor canthen be converted into a conductive film element of the presentinvention after appropriate treatment or processing steps describedbelow.

The conductive film element precursors consist essentially of oneessential layer on each supporting side of the substrate, whichessential layer a non-color hydrophilic photosensitive layer disposed onthe transparent substrate. This essential layer can be disposed on onlyone supporting side of the transparent substrate, but in many duplexembodiments, it is disposed on both first and opposing second supportingsides of the transparent substrate. Hydrophilic overcoats describedbelow are optional but highly desired in many embodiments, and suchhydrophilic overcoats are disposed directly on the non-color hydrophilicphotosensitive layer. These layers can be disposed on only onesupporting side of the transparent substrate, or they can be disposed onboth first supporting and opposing second supporting sides of thetransparent substrate, in the same order. Other optional layers can alsobe present on either or both supporting sides as described below.

Transparent Substrates:

The choice of transparent substrate generally depends upon the intendedutility of the resulting conductive film element. It can be rigid orflexible, and generally transparent as described above. For example, thesubstrate can be a transparent, flexible substrate having an integratedtransmittance of at least 80% and generally at least 95% as measuredusing a standard spectrophotometer and procedures over the noted visibleregion of the electromagnetic spectrum as described above.

Suitable transparent substrates include but are not limited to, glass,glass-reinforced epoxy laminates, cellulose triacetate or anothercellulose ester, acrylic esters, polycarbonates, adhesive-coated polymersubstrates, polymer substrates (such as polyester films), and compositematerials. Suitable polymers for use as polymer substrates include butare not limited to, polyethylene, polyesters such as polyethyleneterephthalate (PET) and polyethylene naphthalate (PEN), polypropylenes,polyvinyl acetates, polyurethanes, polyamides, polyimides, polysulfones,and mixtures thereof.

Polymeric substrates can also comprise two or more layers of the same ordifferent polymeric composition so that the composite substrate (orlaminate) has the same or different layer refractive properties. Thetransparent substrate can be treated on either or both supporting sidesto improve adhesion of a silver salt emulsion or dispersion to one orboth supporting sides of the substrate. For example, the transparentsubstrate can be coated with a polymer adhesive layer, chemicallytreated, or subjected to a corona treatment on one or both supportingsides.

Biaxially-oriented sheets, while described as having at least one layer,can also be provided with additional layers that can serve to change theoptical or other properties of the biaxially-oriented sheet. Such layersmight contain tints, antistatic or conductive materials, or slip agents.The biaxially-oriented extrusion can be carried out with as many as 10layers if desired to achieve some particular desired property.

Particularly useful transparent substrates for the manufacture offlexible electronic devices or touch screen components are flexible,which feature aids rapid roll-to-roll application. Estar® poly(ethyleneterephthalate) films and cellulose triacetate films are particularlyuseful materials for making flexible transparent substrates for thisinvention.

The transparent substrate can be the same as a support or film that isalready incorporated into a flexible display device, by which it ismeant that essential layers described herein are applied to atransparent substrate material within a display device and imaged insitu according to a desired pattern, and then processed in situ.

Where a discrete transparent substrate is utilized (that is, thetransparent substrate is not already incorporated in a flexible displaydevice), the layers (from formulations) are provided on to one or bothsupporting sides thereof. If different patterns (or grids) are intendedfor each supporting side, the substrate or optional intervening filter(or antihalation) layers comprising filter dyes can be provided toprevent light exposure from one side reaching the other. Alternatively,the silver halide emulsions can be sensitized differently for theopposing non-color hydrophilic photosensitive layers on opposingsupporting sides of the transparent substrate.

The transparent substrate used in the conductive film element precursorcan have a thickness of at least 20 μm and up to and including 300 μm ortypically at least 75 μm and up to and including 200 μm. Antioxidants,brightening agents, antistatic or conductive agents, plasticizers, andother known additives can be incorporated into the transparentsubstrate, if desired, in amounts that would be readily apparent to oneskilled in the art.

Non-Color Hydrophilic Photosensitive Layers:

The essential silver halide(s) in these layers comprise silver cationsof one or more silver halides that can be converted into silver metalparticles according to a desired pattern upon exposure of each non-colorhydrophilic photosensitive layer in an imagewise fashion. The latentimage can then be developed into a silver metal image using known silverdevelopment procedures and chemistry (described below). The silverhalide (or combination of silver halides) is photosensitive, meaningthat radiation from UV to visible light (for example, of at least 200 nmand up to and including 750 nm radiation) is generally used to convertsilver cations to silver metal particles in a latent image. In someembodiments, the silver halide is present in combination with athermally-sensitive silver salt (such as silver behenate) and thenon-color photosensitive hydrophilic layer can be both photosensitiveand thermally sensitive (sensitive to imaging thermal energy such asinfrared radiation).

The useful photosensitive silver halides can be, for example, silverchloride, silver bromide, silver chlorobromoiodide, silverbromochloroiodide, silver chlorobromide, silver bromochloride, or silverbromoiodide that are prepared as individual compositions (or emulsions).The various halides are listed in the silver halide name in descendingorder of halide amount. In addition, individual silver halide emulsionscan be prepared and mixed to form a mixture of silver halide emulsionsthat are used on the same or different supporting sides of thesubstrate. In general, the useful silver halides can comprise up to andincluding 100 mol % of chloride or up to and including 100 mol % ofbromide, and up to and including 5 mol % iodide, all based on totalsilver.

The silver halide grains used in each non-color hydrophilicphotosensitive layer generally can have an ESD of at least 30 nm and upto and including 300 nm, or more likely at least 50 nm and up to andincluding 200 nm.

The coverage of total silver in the silver halide(s) in each non-colorhydrophilic photosensitive layer can be at least 2500 mg Ag/m² andtypically at least 3500 mg Ag/m² and up to any amount but generally lessthan 5000 mg Ag/m², for example up to and including 4900 mg Ag/m².Higher silver coverage can be used if desired.

The dry thickness of each non-color hydrophilic photosensitive layer canbe generally at least 0.5 μm and up to and including 12 μm, andparticularly at least 0.5 μm and up to and including 7 μm.

The final dry non-color hydrophilic photosensitive layer can be made upof one or more individually coated non-color hydrophilic photosensitivesub-layers that can be applied using the same or different silver halideemulsion formulations. Each sub-layer can be composed of the same ordifferent silver halide(s), hydrophilic binders or colloids, andaddenda. The sub-layers can have the same or different amount of silvercontent.

The photosensitive silver halide(s) used in the first non-colorhydrophilic photosensitive layer can be the same or different from thephotosensitive silver halide(s) used in the opposing second supportingside non-color hydrophilic photosensitive layer.

The photosensitive silver halide grains (and any addenda associatedtherewith as described below) are dispersed (generally uniformly) in oneor more suitable hydrophilic binders or colloids to form a hydrophilicsilver halide emulsion. Examples of such hydrophilic binders or colloidsinclude but are not limited to, gelatin and gelatin derivatives,polyvinyl alcohol (PVA), poly(vinyl pyrrolidone) (PVP), casein, andmixtures thereof. Suitable hydrophilic colloids and vinyl polymers andcopolymers are also described in Section IX of Research Disclosure Item36544, September 1994 that is published by Kenneth Mason Publications,Emsworth, Hants, PO10 7DQ, UK.

The amount of hydrophilic binder or colloid in each non-colorhydrophilic photosensitive layer can be adapted to the particular drythickness that is desired as well as the amount of silver halide that isincorporated. It can also be adapted to meet desired dispersibility,swelling, and layer adhesion to the transparent substrate. In general,the one or more hydrophilic binders or colloids can be present in anamount of at least 10 weight % and up to and including 95 weight % basedon the total solids in the emulsion formulation or dry layer.

Some useful non-color hydrophilic photosensitive layer compositions havea relatively high silver ion/low hydrophilic binder (for example,gelatin) weight ratio. For example, a particularly useful weight ratioof silver ions (and eventually silver metal) to hydrophilic binder orcolloid such as gelatin (or its derivative) can be at least 0.1:1, oreven at least 1.5:1 and up to and including 10:1. A particularly usefulweight ratio of silver ions to the hydrophilic binder or colloid can beat least 2:1 and up to and including 5:1. Different ratios can be usedif desired for a given purpose.

The hydrophilic binder or colloid can be used in combination with one ormore hardeners designed to harden the particular hydrophilic binder suchas gelatin. Particularly useful hardeners for gelatin and gelatinderivatives include but are not limited to, non-polymeric vinyl-sulfonessuch as bis(vinyl-sulfonyl) methane (BVSM), bis(vinyl-sulfonyl methyl)ether (BVSME), and 1,2-bis(vinyl-sulfonyl acetamide)ethane (BVSAE).Mixtures of hardeners can be used if desired. The hardeners can beincorporated into each non-color hydrophilic photosensitive layer in anysuitable amount that would be readily apparent to one skilled in theart.

In general, each non-color hydrophilic photosensitive layer can have aswell ratio of at least 150% as determined by optical microscopy ofelement cross-sections. Swelling can be controlled by the amount ofhardening that is carried out with appropriate amounts of hardenerswithin the photosensitive silver halide emulsion layer or within variousprocessing solutions (described below).

If desired, the useful silver halide described above is sensitized toany suitable wavelength of exposing radiation. Organic sensitizing dyescan be used, but it can be advantageous to sensitize the silver salt tothe UV portion of the electromagnetic spectrum without using visiblelight sensitizing dyes to avoid unwanted dye stains in the conductivearticle is intended to have high transparency. Alternatively, the silverhalides can be used without spectral sensitization beyond theirintrinsic spectral sensitivities.

Non-limiting examples of addenda useful to be included with the silverhalides, including chemical and spectral sensitizers, filter dyes,organic solvents, thickeners, dopants, emulsifiers, surfactants,stabilizers, hardeners, and antifoggants are described in ResearchDisclosure Item 36544, September 1994 and the many publicationsidentified therein. Such materials are well known in the art and itwould not be difficult for a skilled artisan to formulate or use suchcomponents for purposes described herein. Some useful silver saltemulsions are described, for example in U.S. Pat. No. 7,351,523(Grzeskowiak), U.S. Pat. No. 5,589,318, and U.S. Pat. No. 5,512,415(both to Dale et al.).

Useful silver halide emulsions containing silver halide grains that canbe reduced to silver metal particles can be prepared by any suitablemethod of grain growth, for example, by using a balanced double run ofsilver nitrate and salt solutions using a feedback system designed tomaintain the silver ion concentration in the growth reactor. Knowndopants can be introduced uniformly from start to finish ofprecipitation or can be structured into regions or bands within thesilver halide grains. Useful dopants include but are not limited to,osmium dopants, ruthenium dopants, iron dopants, rhodium dopants,iridium dopants, and cyanoruthenate dopants. A combination of osmium andiridium dopants such as a combination of osmium nitrosyl pentachlorideand iridium dopant is useful. Such complexes can be alternativelyutilized as grain surface modifiers in the manner described in U.S. Pat.No. 5,385,817 (Bell). Chemical sensitization can be carried out by anyof the known silver halide chemical sensitization methods, for exampleusing thiosulfate or another labile sulfur compound alone, or incombination with gold complexes.

Useful silver halide grains can be rounded cubic, cubic-rounded,octahedral, rounded octahedral, polymorphic, tabular, or thin tabularemulsion grains. Such silver halide grains can be regular untwinned,regular twinned, or irregular twinned with cubic or octahedral faces. Inone embodiment, the silver halide grains can be rounded cubic having anedge length of less than 0.5 μm and at least 0.05 μm.

Antifoggants and stabilizers can be added to give the silver halideemulsion the desired sensitivity, if appropriate. Antifoggants that canbe used include, for example, azaindenes such as tetraazaindenes,tetrazoles, benzotriazoles, imidazoles and benzimidazoles.

The essential silver halide grains and hydrophilic binders or colloids,and optional addenda can be formulated and coated as a silver halideemulsion using suitable emulsion solvents including water andwater-miscible organic solvents. For example, useful solvents for makingthe silver halide emulsion or coating formulation can be water, analcohol such as methanol, a ketone such as acetone, an amide such asformamide, a sulfoxide such as dimethyl sulfoxide, an ester such asethyl acetate, an ether, a liquid polyvinyl alcohol, liquid or lowmolecular weight poly(vinyl alcohol), or combinations of these solvents.The amount of one or more solvents used to prepare the silver halideemulsions can be at least 30 weight % and up to and including 50 weight% of the total formulation weight. Thus, such coating formulations canbe prepared using any of the photographic emulsion making proceduresthat are known in the art.

Hydrophilic Overcoats

While the non-color hydrophilic photosensitive layer can be theoutermost layer in the precursor, in many embodiments, a hydrophilicovercoat can be disposed over each non-color hydrophilic photosensitivelayer, on either or both supporting sides of the transparent substrate.This hydrophilic overcoat can be the outermost layer in the conductivefilm element precursor (that is, there are no layers purposely placedover it on either or both supporting sides of the transparentsubstrate). Thus, generally if both supporting sides of the transparentsubstrate are used to provide a conductive silver pattern, then ahydrophilic overcoat can be present on both supporting sides of thetransparent substrate. Thus, a first hydrophilic overcoat can bedisposed over the first non-color hydrophilic photosensitive layer, anda second hydrophilic overcoat can be disposed over a second non-colorsecond hydrophilic photosensitive layer on the opposing supporting sideof the substrate.

In most embodiments, each hydrophilic overcoat can be directly disposedon each non-color hydrophilic photosensitive layer, meaning that thereare no intervening layers on the supporting sides of the transparentsubstrate. The chemical compositions and dry thickness of thesehydrophilic overcoats can be the same or different, but in mostembodiments they have essentially the same chemical composition and drythickness on both supporting sides of the transparent substrate.

In some embodiments, each hydrophilic overcoat (first or second, orboth) can comprise one or more silver halides in the same or differentamount so as to provide silver metal particles, after exposure andprocessing, in an amount of at least 5 mg Ag/m² and up to and including150 mg Ag/m², or at least 5 mg Ag/m² and up to and including 100 mgAg/m².

This silver halide can be dispersed (generally uniformly) within one ormore hydrophilic binders or colloids in each hydrophilic overcoat, whichhydrophilic binders or colloids include those described above for thenon-color hydrophilic photosensitive layers. In many embodiments, thesame hydrophilic binders or colloids can be used in all of the layers ofthe conductive film element precursor. However, different hydrophilicbinders or colloids can be used in the various layers, and on either orboth supporting sides of the supporting substrate. The amount of one ormore hydrophilic binders or colloids in each hydrophilic overcoat can bethe same or different and generally at least 50 weight % and up to andincluding 97 weight %, based on total hydrophilic overcoat dry weight.

The hydrophilic overcoat can include one or more radiation absorberssuch as UV radiation absorbers in an amount of at least 5 mg/m² and upto and including 100 mg/m². Useful UV radiation absorbers can be“immobilized” so that they do not readily diffuse out of the hydrophilicovercoat.

Each hydrophilic overcoat can also comprise one or more hardeners for ahydrophilic binder or colloid (such as gelatin or a gelatin derivative).Useful hardeners are described above.

It is also possible that the silver halide(s) in each hydrophilicovercoat is the same as the silver halide(s) in each non-colorhydrophilic photosensitive layer over which it is disposed.

Moreover, the one or more silver halides in each hydrophilic overcoatcan have a grain ESD of at least 30 nm and up to and including 1000 nm,or at least 30 nm and up to and including 300 nm.

In some embodiments, the one or more silver halides in each hydrophilicovercoat has a grain ESD that is larger than the grain ESD of the silverhalide in the non-color hydrophilic photosensitive layer over which itis disposed.

The dry thickness of the each hydrophilic overcoat can be at least 100nm and up to and including 800 nm or more particularly at least 300 nmand up to and including 500 nm. In many embodiments, the grain ESD todry thickness ratio in the hydrophilic overcoat can be from 0.25:1 toand including 1.75:1 or more likely from 0.5:1 to and including 1.25:1.

In various embodiments, the silver halide(s) in each hydrophilicovercoat can comprise up to 100 mol % bromide or up to 100 mol %chloride, and up to and including 3 mol % iodide, all molar amountsbased on total silver content.

In other embodiments, the silver halide(s) in each hydrophilic overcoatcan comprise more chloride than the silver halide in the non-colorhydrophilic photosensitive layer over which it is disposed. Thisrelationship can be the same or different on both supporting sides ofthe substrate in such “duplex” conductive film element precursors.

In useful embodiments, the silver halide(s) in each hydrophilic overcoatcan comprise at least 80 mol % bromide, and the remainder is chloride oriodide, based on total silver content, and the silver halide(s) in thenon-color hydrophilic photosensitive layer over which it is disposed canhave at least 80 mol % bromide, and the remainder is iodide or chloride,all based on total silver content.

It is also useful in conductive film element precursors of the presentinvention that the silver halide(s) in the each hydrophilic overcoat andthe silver halide(s) in each non-color hydrophilic photosensitive layerover which it is disposed are matched in photographic speed. This isbest achieved when the exposure sensitivity of the silver halideemulsion(s) in the hydrophilic overcoat can be at least 10% and up toand including 200% of the optimum sensitivity of silver halide emulsionin the underlying non-color hydrophilic photosensitive layer used toprovide the conductive silver pattern, as expressed in

Additional Layers:

In addition to the layers and components described above on one or bothsupporting sides of the transparent substrate, the conductive filmelement precursor used in the practice of this invention can alsoinclude other layers that are not essential but can provide someadditional properties or benefits, such as radiation absorbing filterlayers, adhesion layers, and other layers as are known in thephotographic art. The radiation absorbing filter layers can also beknown as “antihalation” layers that can be located between the essentiallayers on each supporting side of the transparent substrate. Forexample, each supporting side can have a radiation absorbing filterlayer disposed directly on it, and directly disposed underneath thenon-color hydrophilic photosensitive layer.

Such radiation absorbing filter layers can include one or more filterdyes that absorb in the UV, red, green, or blue regions of theelectromagnetic spectrum, or any combination thereof, and such radiationabsorbing filter layers can be on located between the substrate and thenon-color hydrophilic photosensitive layer on one or both supportingsides of the transparent substrate.

For example, the conductive film element precursor can comprise an UVabsorbing layer between a first supporting side of the transparentsubstrate and the first non-color hydrophilic photosensitive layer.

The duplex conductive film element precursors further comprise on theopposing second supporting side of the transparent substrate, a secondnon-color hydrophilic photosensitive layer and a second hydrophilicovercoat disposed over the second non-color hydrophilic photosensitivelayer. A radiation (for example, UV) absorbing filter layer can bedisposed between the or opposing second supporting side of thetransparent substrate and the second non-color hydrophilicphotosensitive layer, which radiation absorbing layer can be the same asor different from the radiation absorbing filter layer on the firstsupporting side of the transparent substrate.

In many duplex embodiments, the second non-color hydrophilicphotosensitive layer and the second hydrophilic overcoat have the samecomposition as the first non-color hydrophilic photosensitive layer andthe first hydrophilic overcoat, respectively.

Thus, in some embodiments, the conductive film element precursor canfurther comprise, on the opposing second supporting side of thetransparent substrate, a second non-color hydrophilic photosensitivelayer and optionally, a second hydrophilic overcoat disposed over thesecond non-color hydrophilic photosensitive layer.

For example, the second non-color hydrophilic photosensitive layer andthe second hydrophilic overcoat can have the same composition as thefirst non-color hydrophilic photosensitive layer and the firsthydrophilic overcoat, respectively.

In other embodiments, the exposure sensitivity of the silver halideemulsion in the first hydrophilic overcoat can be at least 10% and up toand including 200% of the optimum sensitivity of the silver halideemulsion in the first non-color hydrophilic photosensitive layer, asexpressed as μJ/m², and the exposure sensitivity of the silver halideemulsion in the second hydrophilic overcoat can be at least 10% and upto and including 200% of the optimum sensitivity of the silver halideemulsion in the second non-color hydrophilic photosensitive layer, asexpressed as pJ/m². The optimum sensitivities of the respective sides ofthe transparent substrate can be the same or different.

Preparing Conductive Film Element Precursors

The various layers are formulated using appropriate components andcoating solvents and are applied to one or both supporting sides of asuitable transparent substrate (as described above) using known coatingprocedures including those commonly used in the photographic industry(for example, bead coating, blade coating, curtain coating, spraycoating, and hopper coating). Each layer can be applied to eachsupporting side of the transparent substrate in single-pass proceduresor simultaneous multi-layer coating procedures.

Providing Conductive Film Elements

The conductive film element precursors are provided for use in themethod of this invention and then imagewise exposed to provide a latentsilver metal image in the non-color hydrophilic photosensitive layerseither or both supporting sides of the transparent substrate. Imagewiseexposure also reduces any silver halide(s) present in the hydrophilicovercoat(s) to silver metal particles. The conductive film elementprecursors can be used immediately for an intended purpose, or they canbe stored in roll or sheet form for later use. For example, theprecursors can be rolled up during manufacture and stored for use in aroll-to-roll imaging and processing process, and subsequently cut intodesired sizes and shapes.

More commonly, photosensitive silver halides in each non-colorhydrophilic photosensitive layer can be imagewise exposed to appropriateactinic radiation (UV to visible radiation) from a suitable source thatare well known in the art, and then developed (silver ions reduced tosilver metal particles) as described below. Such exposure provides animagewise exposed precursor comprising a latent silver image in thefirst non-color hydrophilic photosensitive layer, and also a latentsilver image in the second non-color hydrophilic photosensitive layer ifit is present in the precursor.

In some embodiments, the exposure processes are controlled so that anyexposing radiation for the non-color hydrophilic photosensitive layer onone supporting side of the transparent substrate does not reach anynon-color hydrophilic photosensitive layer on the opposing secondsupporting side of the transparent substrate. This result can beachieved in various ways as described for example in U.S. PatentApplication 2011/0289771 (Kuriki) the disclosure of which isincorporated herein by reference. It is particularly useful to include aradiation filter dye layer or antihalation layer on both sides of thetransparent substrate, which layer is arranged between the transparentsubstrate and each (first and second) non-color hydrophilicphotosensitive layer, and the exposing is carried out using radiationdirected at the conductive film element precursor from the first (orsecond, or both) supporting side of the transparent substrate.

Processing with a Silver Halide Developing Solution:

A first processing treatment can be carried out using a silver halidedeveloping solution that has a pH of at least 8 and up to and including13, or more typically of at least 10 and up to and including 11. The pHcan be provided using known alkaline reagents along with the compoundsdescribed below.

A first essential component of this silver halide developing solution isone or more primary developing agents such as a hydroquinone or aderivative thereof, or an ascorbic acid or a derivative thereof. Usefulhydroquinone or derivatives (also known as polyhydroxybenzenes) includebut are not limited to, hydroquinone, cathecol, pyrogallol,methylhydroquinone, chiorohydroquinone, hydroquinonemonosulfate,1,2-naphthalenediol, and 1,4-naphthalenediol. Useful ascorbic acid andderivatives include but are not limited to, ascorbic acid, erythrobicacid and its derivatives, sodium ascorbate, and sodium erythrobate.

The one or more primary developing agents can be present in the silverhalide developing solution in a total amount of at least 0.01 mol/l andup to and including 1 mol/l, at least 0.01 mol/l and up to and including0.15 mol/l, or more typically of at least 0.075 mol/l and up to andincluding 0.14 mol/l. As noted above, mixtures of primary developingagents can be used if desired and in such embodiments, theseconcentrations refer to the total amount of the primary developingagent.

The silver halide developing solution also comprises one or morecatalytic developing agents as a second essential component, and suchcompounds are p-aminophenols or derivatives thereof or a phenidone(including derivatives of phenidone). Such catalytic developing agentscan be present in the silver halide developing solution in a totalamount of at least 0.001 mol/l and up to and including 0.1 mol/l, atleast 0.001 mol/l and up to and including 0.025 mol/l, or typically ofat least 0.001 and up to and including 0.002 mol/l. When mixtures ofthese compounds are used, the concentrations refer to the total amountsof catalytic developing agents.

Compared to the primary developing agents that are the primary silverion developing agents (reducing agents), the presence of the catalyticdeveloping agent is desired in order to increase the kinetics ofdevelopment, especially by reducing or eliminating development inductiontime.

Useful p-aminophenols include but are not limited to,p-methylaminophenol, p-aminophenol, m-chloro-p-aminophenol,m-methyl-p-aminophenol, and p-hydroxyphenylglycine. Useful phenidone andderivatives include but are not limited to, substituted or unsubstitutedphenidone such as 4,4-dimethyl-3-pyrazolidinone (dimezone) and4-(hydroxymethyl)-4-methyl-1-phenyl-3-pyrazolidinone (HMMP).

In general, the concentration of the one or more catalytic developingagents can be less than the concentration of the one or more primarydeveloping agents. More particular, the total concentration of the oneor more primary developing agents can be at least 100 times the totalconcentration of the one or more catalytic developing agents.

In many embodiments, the silver halide developing solution hashydroquinone or a derivative thereof as the primary developing agent andphenidone as the catalytic developing agent.

Important optional components of the silver halide developing solutioninclude but are not limited to, one or more alkali metal sulfites andone or more development inhibitors or restrainers such as alkali metalhalides, substituted or unsubstituted mercaptotetrazoles, one or morebenzotriazoles, one or more aryl or alkyl disulfides, and one or morearyl or alkyl thiols. Mixtures of any of the same or different classesof compounds can be used.

For example, useful alkali metal sulfites include sodium sulfite,potassium sulfite, and mixtures thereof. The alkali metal sulfites canbe present in the silver halide developing solution in a total amount ofat least 0.1 mol/l and up to and including 1 mol/l or typically of atleast 0.4 mol/l and up to and including 0.8 mol/l. This concentrationrefers to the total amount of all sulfites if a mixture of compounds isused.

The one or more development inhibitors or restrainers, such as at leastone of any of an alkali metal halide, an arylmercaptotetrazole, abenzotriazole, and an aryl or alkyl disulfide, or an aryl or alkylthiol, can be present in the silver halide developing solution in atotal amount of at least 0.25 mmol/l and up to and including 2.5 mmol/lor typically of at least 0.5 mmol/l and up to and including 1.5 mmol/l.

Useful alkali metal halides include but are not limited to, sodiumchloride, sodium bromide, potassium chloride, and potassium bromide.

Useful substituted or unsubstituted arylmercaptotetrazoles includecompounds include but are not limited to, 1-phenyl-5-mercaptotetrazole(PMT), 1-ethyl-5-mercaptotetrazole, 1-t-butyl-5-mercaptotetrazole, and1-pyridinyl-5-mercaptotetrazoles.

Useful benzotriazoles include but are not limited to, substituted andunsubstituted benzotriazole compounds such as benzotriazole,5-methylbenzotriazole, and 5,6-dichlorobenzotriazole.

Useful aryl or alkyl disulfides include but are not limited to,5,5′-(dithiobis(4,1-phenyleneimino))bis(5-oxo-pentanoic acid) and itsdisodium salt, 2,2′-diethiobisbenzoic acid and its disodium salt, and5,5′-dithiobis(pentanoic acid) and its disodium salt.

Useful aryl or alkyl thiols include but are not limited to,5-mercapto-4,1-phenylimino-5-oxo-pentanoic acid and its sodium salt and5-mercaptopentanoic acid and its sodium salt.

Other addenda that can be present in the silver halide developingsolution in known amounts include but are not limited to, metalchelating agents, preservatives (besides the sulfites), biocides,antioxidants, small amounts of water-miscible organic solvents (such asbenzyl alcohol and diethylene glycol), nucleators, acids, bases (such asalkali hydroxides), and buffers (such as carbonate, borax, phosphates,and other basic salts).

The silver halide developing solution can be provided at workingstrength or in a concentrated form that can be suitably diluted prior toor during processing using known processing equipment and procedures.For example, the silver halide developing solution can be concentratedat least 5 times compared to a desired working strength concentration.

Thus, the silver halide developing solution can be used to process ortreat the imagewise exposed precursor for a suitable time and at asuitable temperature, at generally atmospheric pressure to achievedevelopment of at least 75 mol %, and typically at least 90 mol % of theexposed silver ion in the imagewise exposed first (or second) non-colorhydrophilic photosensitive layer, as well as at least 90 mol % of anysilver ion in each hydrophilic overcoat that can be present.

For example, the processing temperatures for using the silver halidedeveloping solution can range from at least 15° C. and up to andincluding 60° C. or typically of at least 35° C. and up to and including45° C. Useful processing times can range from at least 10 seconds and upto and including 10 minutes but more likely up to and including 1minute. A skilled worker could use routine experimentation to find theoptimum processing conditions to achieve the desired results in reducingthe silver ion to silver metal in the latent image. A washing or rinsingtreatment using water or a suitable aqueous solution can be carried outfor a suitable time and at a suitable temperature after this processingfeature and before processing with the silver halide solution physicaldeveloping solution.

Processing with Silver Halide Solution Physical Developing Solution:

After an optional washing, the imagewise exposed precursor is thengenerally processed in a silver halide solution physical developingsolution to improve conductivity of the silver image, for example, thepredetermined silver metal pattern on one or both sides of thesupporting sides of the substrate.

The silver halide solution physical developing solution generally canhave a pH of at least 8 and up to and including 13 or typically of atleast 8 and up to and including 12. The pH can be provided using knownalkaline reagents along with the compounds described below.

This silver halide solution physical developing solution comprises oneor more primary developing agents as an essential component, chosen fromone or more of hydroquinone or its derivatives or one or more ascorbicacid or derivatives thereof. Examples of such compounds are providedabove. The primary developing agents in the silver halide solutionphysical developing solution can be the same or different as the primarydeveloping agents in the silver halide developing solution describedabove.

The one or more primary developing agents in the silver halide solutionphysical developing solution can be present in a total amount of atleast 0.01 mol/l and up to and including 1 mol/l or typically of atleast 0.05 mol/l and up to and including 0.2 mol/l. This concentrationrefers to the total amount of primary developing agents if a mixture ofsuch compounds is used.

In addition, the silver halide solution physical developing solutioncomprises one or more silver halide dissolution catalysts as essentialcomponents in an amount of at least 0.001 mol/l and up to and including0.1 mol/l, or typically of at least 0.005 mol/l and up to and including0.05 mol/l. These concentrations refer to the total amount of silverhalide dissolution catalysts when a mixture of such compounds is used.

Useful silver halide dissolution catalysts include but are not limitedto, alkali metal thiocyanate salts such as sodium thiocyanate andpotassium thiocyanate, thioethers such as 3,6-dithia-1,8-octanediol, andheterocyclic thiones such astetrahydro-4,6-dimethyl-1,3,5-triazine-2(1H)-thione, andtetrahydro-3-hydroxyethyl-1,3,5-triazine-2(1H)-thione. These compoundscan readily complex with silver.

The silver halide solution physical developing solution used in thepresent invention contains substantially no catalytic developing agentssuch as those compounds described above for the silver halide developingsolution. The term “substantially no” means that less than 0.001 mol/lor even less than 0.0001 mol/l of such compounds are purposelyincorporated into or created in the solution.

The silver halide solution physical developing solution can furthercomprise one or more alkali metal sulfites include sodium sulfite,potassium sulfite, and mixtures thereof. The alkali metal sulfites canbe present in the silver halide solution physical developing solution ina total amount of at least 0.2 mol/l and up to and including 3 mol/l ortypically of at least 0.5 mol/l and up to and including 1 mol/l whenpotassium sulfite or sodium sulfite is used or particularly when onlypotassium sulfite is used. These concentrations refer to the totalamount of all sulfites if a mixture of compounds is used.

The silver halide solution physical developing solution can furtherinclude one or more polyaminopolycarboxylic acid salts that are capableof complexing with silver ion, including but not limited to,diethylenetriamine pentaacetic acid, pentasodium salt and other similarcompounds known in the art. Such compounds can be useful particularlywhen a sulfite is not present. Such compounds can be present in anamount of at least 0.001 mol/l and up to and including 0.03 mol/l.

The silver halide solution physical developing solution can also includeone or more metal ion complexing agents that can complex with silver,calcium, iron, magnesium, or other metal ions that can be present.Silver or calcium metal ion complexing agents can be particularly usefulin a total amount of at least 0.001 mol/l.

Particularly useful silver halide solution physical developing solutionsinclude but are not limited to, hydroquinone or a derivative thereof andsodium thiocyanate or potassium thiocyanate, and optionally a sulfiteand calcium or silver metal ion complexing agent.

The silver halide physical solution developing solution can be providedat working strength or in a concentrated form that is suitably dilutedprior to or during processing using known processing equipment andprocedures. For example, the silver halide physical developing solutioncan be concentrated at least 4 times compared to a desired workingstrength concentration.

Thus, the silver halide solution physical developing solution is used toprocess or treat the imagewise exposed precursor for a suitable time andat a suitable temperature, at generally atmospheric pressure to providea conductivity of the resulting first silver image that is as least 2times the conductivity of the first silver image (or second silverimage) after processing the imagewise exposed precursor only with thesilver halide developing solution.

The conductivity measurements of the first silver image are obtained asdescribed below in the Examples.

For this processing feature, the temperature can range from at least 20°C. and up to and including 60° C. or typically of at least 35° C. and upto and including 45° C. Useful processing times can range from at least30 seconds and up to and including 6 minutes but more likely at least 2minutes and up to and including 4 minutes. A skilled worker could useroutine experimentation to find the optimum processing conditions toachieve the desired conductivity results. A washing or rinsing treatmentusing water or a suitable aqueous solution can be carried out for asuitable time and at a suitable temperature after this processingfeature and before the treatment with the fixing solution.

In many embodiments, the same silver halide developing solution, silverhalide solution physical developing solution and fixing solution areused for forming the first and second silver images after imagewiseexposure of both sides.

Fixing:

After processing with the silver halide solution physical developingsolution and optional washing, remaining undeveloped silver ions (in anylayer) can be removed by treating the imagewise exposed and developedprecursor with a fixing solution. Fixing solutions are well known in theblack-and-white photographic art and contain one or more compounds thatcomplex the silver halide for removal from the layers in which it ispresent. Thiosulfate salts are commonly used in fixing solutions. Thefixing solution can optionally contain a hardening agent such as alum orchrome-alum. The developed film can be processed in a fixing solutionimmediately after the silver halide solution physical development, orthere can be an intervening stop bath or water wash or both. Fixing canbe carried out at any suitable temperature and time such as at least 20°C. for at least 30 seconds.

After fixing, the article containing the first silver image (andoptional second silver image) can be washed or rinsed in water that canoptionally include surfactants or other materials to reduce water spotformation upon drying, which is optional before the next processingfeature. Drying can be accomplished in ambient or by heating, forexample, in a convection oven at a temperature above 50° C. but belowthe glass transition temperature of the substrate.

Fixing then leaves the silver metal particles in the first silver image(generally in a silver pattern) in each formerly non-color hydrophilicphotosensitive layer. This fixing also removes any non-developed silverions in each hydrophilic overcoat. The same effects are provided on theopposing second supporting side for the duplex conductive film elementprecursors described herein.

It is desired that, after processing in the fixing solution, theresulting conductive film element exhibits a (visual) D_(min) of lessthan or equal to 0.03.

After fixing, the article can be washed or rinsed in water that canoptionally include surfactants or other materials to reduce water spotformation upon drying.

Conductivity Enhancement:

After fixing and optional rinsing and before drying as described above,the article comprising the first silver image (and optional secondsilver image) can be further washed or rinsed with water and thentreated to further enhance the electrical conductivity of the silvermetal particles in each silver image on each supporting side of thesubstrate. A variety of ways have been proposed to carry out this“conductivity enhancement” process. For example, U.S. Pat. No. 7,985,527(Tokunaga) and U.S. Pat. No. 8,012,676 (Yoshiki et al.) describetreatments using hot water baths, water vapor, reducing agents, orhalides. The details of such treatments are provided in these patents,the disclosures of which are incorporated herein by reference.

It is also possible enhance electrical conductivity of the silver metalparticles in each silver image by repeated contact (treatment) with aconductivity enhancing agent followed by optional washing and drying,and repeating this cycle of treating for conductivity enhancement withoptional washing and drying generally one or more times. Usefulconductivity enhancing agents include but are not limited to, sulfites,borane compounds, hydroquinones, p-phenylenediamines, and phosphites.This treatment can be carried out at a temperature of at least 30° C.and up to and including 90° C. for at least 0.25 minute and up to andincluding 30 minutes.

Additional Treatments:

Prebath solutions can also be used to treat the exposed silver saltsprior to the silver halide development described above. Such prebathsolutions can include one or more development inhibitors as describedabove and in the same or different amounts. Effective developmentinhibitors include but are not limited to, benzotriazoles, heterocyclicthiones, and mercaptotetrazoles. The prebath temperature can be in arange as described above for the silver halide development step. Prebathtime depends upon concentration and the particular inhibitor, but it canrange from at least 10 seconds and up to and including 4 minutes.

It can be useful in some embodiments to treat the conductive filmelement with a hardening bath after fixing and before drying to improvethe physical durability of the resulting conductive film element. Suchhardening baths can include one or more known hardening agents inappropriate amounts that would be readily apparent to one skilled in theart.

Additional treatments of the conductive film element, such as treatmentwith a stabilizing bath, can also be carried out before a final dryingif desired, at any suitable time and temperature.

The method of this invention can be carried out using a conductive filmelement precursor comprising on both first and opposing secondsupporting sides of the substrate, suitable first and second non-colorhydrophilic photosensitive layers and first and second hydrophilicovercoats disposed over the first and second non-color hydrophilicphotosensitive layers, respectively, the first and second hydrophilicovercoats being the outermost layers on the respective first supportingand opposing second supporting sides of the substrate.

In such methods, both first and second non-color hydrophilicphotosensitive layers are appropriately exposed to provide the same ordifferent (usually different) latent patterns containing silver halidein the first and second non-color hydrophilic photosensitive layer.These different exposures can be simultaneous or sequential in manner.In many embodiments, both sides are exposed simultaneously.

The silver halides in the latent images formed in the two opposingnon-color hydrophilic photosensitive layers are then converted to silvermetal particles on both sides during the processing treatments describedabove. Thus, both latent images can be developed and fixedsimultaneously.

Unconverted silver ions can be removed from the first and secondnon-color hydrophilic photosensitive layers, leaving silver metalparticles in the respective first and second patterns corresponding tothe first and second latent patterns on opposing supporting second sidesof the substrate.

During such processes, the same silver halide developing solution,silver halide solution physical developing solution, and fixingsolutions are used for forming both first and second silver images.

Optionally and desirably, the silver metal particles in the patterns onboth sides of the element can be further treated as described above toenhance silver metal conductivity.

In many embodiments, the resulting conductive film element has at leasta predetermined electrically-conductive silver metal electrode grid(pattern) on at least the first supporting side of the substrate anddesirably an electrically-conductive silver metal electrode grid(pattern) on the opposing second supporting side of the substrate thatare different in composition, pattern arrangement, conductive linethickness, or shape of the grid lines (for example, hexagonal,rhombohedral, octagonal, square, circular, or irregular). For example,the electrically-conductive silver metal electrode grid on the firstsupporting side of the substrate can have a square pattern, and theelectrically-conductive silver metal electrode grid on the opposingsupporting second side of the substrate can have a diamond pattern.

The conductive film elements prepared using the present invention can beused as formed, or they can be further treated for example toelectrolessly plate an electrically-conductive metal (such as copper,palladium, platinum, aluminum, tin, or gold) onto the first (and second)silver image. The same or different electrolessly plated conductivemetals can be provided on the first and second silver images on opposingsupporting sides of the substrate.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

1. A method for providing a conductive silver image on a transparentsubstrate in a conductive film element, the method comprising, in order:

imagewise exposing a conductive film element precursor comprising atransparent substrate having a first supporting side and an opposingsecond supporting side, and the conductive film element precursorcomprising on the first supporting side, in order, a first non-colorhydrophilic photosensitive layer comprising photosensitive silverhalide, and optionally a first hydrophilic overcoat disposed over thefirst non-color hydrophilic photosensitive layer, to provide animagewise exposed precursor comprising a first latent silver image inthe first non-color hydrophilic photosensitive layer,

processing the imagewise exposed precursor in a silver halide developingsolution having a pH of at least 8 and up to and including 13, andcomprising: (a) a primary developing agent that is a hydroquinone orascorbic acid or derivative of either, in an amount of at least 0.01mol/l and up to and including 1 mol/l, and (b) a catalytic developingagent that is a p-aminophenol or a phenidone or derivative of either, inan amount of at least 0.001 mol/l and up to and including 0.1 mol/l, forat least 10 seconds, to provide a first silver image corresponding tothe first latent silver image in the first non-color hydrophilicphotosensitive layer,

processing the imagewise exposed precursor in a silver halide solutionphysical developing solution comprising: (a) a primary developing agentthat is a hydroquinone or ascorbic acid or derivative of either, in anamount of at least 0.01 mol/l and up to and including 1 mol/l, and (c) asilver halide dissolution catalyst in an amount of at least 0.001 mol/land up to and including 0.1 mol/l, and substantially no (b) catalyticdeveloping agent, for at least 30 seconds at a temperature of at least20° C., to provide a conductivity of the silver image that is at least 2times the conductivity of the first silver image after only theprocessing with the silver halide developing solution,

processing the imagewise exposed precursor in a fixing solution toremove remaining silver ions and to provide a conductive film elementcontaining the first silver image,

treating the conductive film element to enhance conductivity of thefirst silver image, and

optionally washing and drying the conductive film element.

2. The method of embodiment 1, wherein the conductive film elementexhibits a (visual) D_(min) of less than or equal to 0.03 afterprocessing in the fixing solution.

3. The method of embodiment 1 or 2, wherein the cycle of treating toenhance conductivity and optional washing and drying cycle are repeatedat least once.

4. The method of any of embodiments 1 to 3, wherein the first silverimage is provided in a predetermined conductive silver pattern.

5. The method of any of embodiments 1 to 4, wherein the first non-colorhydrophilic photosensitive layer comprises one or more silver halides toprovide a total silver metal coverage of less than 5000 mg Ag/m².

6. The method of any of embodiments 1 to 5, wherein the conductive filmelement precursor further comprises a first hydrophilic overcoatdisposed over the first non-color hydrophilic photosensitive layer,which first hydrophilic overcoat optionally comprises one or more silverhalides to provide silver metal at a coverage of at least 5 mg Ag/m² andup to and including 150 mg Ag/m² and the one or more silver halides eachhave a grain ESD of at least 30 nm and up to and including 300 nm.

7. The method of embodiment 6, wherein the first hydrophilic overcoatfurther comprises an ultraviolet light absorber.

8. The method of any of embodiments 1 to 7, wherein the exposing iscarried out using radiation directed at the conductive film elementprecursor from the first supporting side of the transparent substrate.

9. The method of any of embodiments 1 to 8, wherein the silver halidedeveloping solution further comprises an alkali metal sulfite in anamount of at least 0.1 mol/l and up to and including 1 mol/l.

10. The method of any of embodiments 1 to 9, wherein the silver halidedeveloping solution further comprises one or more of an alkali metalhalide, an arylmercaptotetrazole, a benzotriazole, an aryl or alkyldisulfide, or an aryl or alkyl thiol.

11. The method of any of embodiments 1 to 10, wherein the silver halidesolution physical developing solution comprises an alkali metalthiocyanate salt as the silver halide dissolution catalyst in an amountof at least 0.001 mol/l and up to and including 0.1 mol/l.

12. The method of any of embodiments 1 to 11, wherein the silver halidesolution physical developing solution further comprises an alkali metalsulfite in an amount of at least 0.2 mol/l and up to and including 3mol/l.

13. The method of any of embodiments 1 to 12, wherein the conductivefilm element precursor further comprises, on the opposing secondsupporting side of the transparent substrate, a second non-colorhydrophilic photosensitive layer and optionally second hydrophilicovercoat disposed over the second non-color hydrophilic photosensitivelayer, and the method further comprises:

imagewise exposing the conductive film element precursor from the secondopposing side of the transparent substrate, to provide a second latentsilver image in the second non-color hydrophilic photosensitive layer ofthe imagewise exposed precursor,

processing the imagewise exposed precursor in the same or differentsilver halide developing solution having a pH of at least 8 and up toand including 13, and comprising: (a) a primary developing agent that isa hydroquinone or ascorbic acid or derivative of either, in an amount ofat least 0.01 mol/l and up to and including 1 mol/l, and (b) a catalyticdeveloping agent that is a p-aminophenol or a phenidone or derivative ofeither, in an amount of at least 0.001 mol/l and up to and including 0.1mol/l, for at least 10 seconds, to provide a second silver imagecorresponding to the second latent silver image in the second non-colorhydrophilic photosensitive layer,

processing the imagewise exposed precursor in the same or differentsilver halide solution physical developing solution comprising: (a) aprimary developing agent that is a hydroquinone or ascorbic acid orderivative of either, in an amount of at least 0.01 mol/l and up to andincluding 1 mat, and (c) a silver halide dissolution catalyst in anamount of at least 0.001 mol/l and up to and including 0.1 mol/l, andsubstantially no (b) catalytic developing agent, for at least 30 secondsat a temperature of at least 20° C., to provide a conductivity of thesilver image that is at least 2 times the conductivity of the secondsilver image after only the processing with the first developingsolution,

processing the imagewise exposed precursor in a fixing solution toremove remaining silver ions and to provide a conductive film elementcontaining the second silver image,

treating the conductive film element to enhance conductivity of thesecond silver image, and

optionally washing and drying the conductive film element.

14. The method of embodiment 13, the conductive film element precursorfurther comprises a second hydrophilic overcoat disposed over the secondnon-color hydrophilic photosensitive layer, which second hydrophilicovercoat optionally comprises one or more silver halides to providesilver metal at a coverage of at least 5 mg Ag/m² and up to andincluding 150 mg Ag/m² and the one or more silver halides each have agrain ESD of at least 30 nm and up to and including 300 nm.

15. The method of embodiment 13 or 14, wherein the same silver halidedeveloping solution, silver halide solution physical developingsolution, and fixing solution are used for forming the first and secondsilver images.

16. The method of any of embodiments 1 to 15, further comprising awashing treatment between processing with the silver halide developingsolution and the silver halide solution physical developing solution.

17. A conductive film element provided by the method of any ofembodiments 1 to 16 having the first silver image on at least the firstsupporting side of the transparent substrate.

18. A conductive film element provided by any of embodiments 1 to 17having the first silver image on the first supporting side of thetransparent substrate and the second silver image on the opposing secondsupporting side of the transparent substrate.

19. The conductive film element of claim 17, further comprising anelectrolessly plated conductive metal on the first silver image.

20. The conductive film element of embodiment 18, further comprising anelectrolessly plated conductive metal on the first silver image, and thesame or different electrolessly plated conductive metal on the secondsilver image.

21. A silver halide developing solution having a pH of at least 8 thatis useful in any of embodiments 1 to 17, the silver halide developingsolution comprising:

(a) a primary developing agent that is a hydroquinone or ascorbic acidor derivative of either in an amount of at least 0.01 mol/l and up toand including 0.15 mol/l,

(b) a catalytic developing agent that is a p-aminophenol or a phenidoneor derivative of either in an amount of at least 0.001 mol/l and up toand including 0.025 mol/l, and

(c) one or more development inhibitors in a total amount of at least0.25 mmol/l and up to and including 2.5 mmol/l.

22. The silver halide developing solution of embodiment 21, furthercomprising an alkali metal sulfite in an amount of at least 0.1 mol/land up to and including 1 mol/l.

23. The silver halide developing solution of embodiment 21 or 22,wherein the one or more development inhibitors comprises one or more ofan alkali metal halide, an arylmercaptotetrazole, a benzotriazole, anaryl or alkyl disulfide, or an aryl or alkyl thiol.

24. The silver halide developing solution of any of embodiments 21 to23, wherein the one or more development inhibitors comprises at leastone of each of an arylmercaptotetrazole, a benzotriazole, and adisulfide in a total amount of at least 0.5 mmol/l and up to andincluding 1.5 mmol/l.

25. The silver halide developing solution of any of embodiments 21 to 24having a pH of at least 10 and up to and including 11.

26. The silver halide developing solution of any of embodiments 21 to25, wherein the primary developing agent is hydroquinone or a derivativethereof, and the catalytic developing agent is a phenidone.

27. The silver halide developing solution of any of embodiments 21 to26, wherein the total concentration of the primary developing agent isat least 100 times the total concentration of the catalytic developingagent.

28. The silver halide developing solution of any of embodiments 21 to 27that is concentrated at least 5 times compared to a desired workingstrength concentration.

29. A silver halide solution physical developing solution useful in themethod of any of embodiments 1 to 27, the silver halide solutionphysical developing solution comprising:

(a) a primary developing agent that is a hydroquinone or ascorbic acidor derivative of either, in an amount of at least 0.01 mol/l and up toand including 1 mol/l, and

(c) a silver halide dissolution catalyst in an amount of at least 0.001mol/l and up to and including 0.1 mol/l, and

the silver halide solution physical developing solution containingsubstantially no (b) catalytic developing agent.

30. The silver halide solution physical developing solution ofembodiment 29, further comprising an alkali metal sulfite in an amountof at least 0.2 mol/l and up to and including 3 mol/l.

31. The silver halide solution physical developing solution ofembodiment 29 or 30, further comprising sodium sulfite or potassiumsulfite in an amount at least 0.5 mol/l and up to and including 1 mol/l.

32. The silver halide solution physical developing solution of any ofembodiments 29 to 31, wherein the silver halide dissolution catalyst isan alkali metal thiocyanate in an amount of at least 0.005 mol/l and upto and including 0.05 mol/l.

33. The silver halide physical developing solution of any of embodiments29 to 32 further comprising one or more metal ion complexing agents in atotal amount of at least 0.001 mol/l.

34. The silver halide physical developing solution of embodiment 33further comprising a calcium or silver metal ion complexing agent as ametal ion complexing agent in a total amount of at least 0.001 mol/l.

35. The silver halide physical developing solution of any of embodiments29 to 34 having a pH of at least 8 and up to and including 12.

36. The silver halide physical developing solution of any of embodiments29 to 35, wherein the primary developing agent is hydroquinone or aderivative thereof, and the silver halide dissolution catalyst is sodiumthiocyanate or potassium thiocyanate.

37. The silver halide physical developing solution of embodiment 36,further comprising a sodium sulfite or potassium sulfite in an amount ofat least 0.5 mol/l and up to and including 1 mol/l.

38. The silver halide physical developing solution of any of embodiments29 to 37 that is concentrated at least 4 times compared to a desiredworking strength concentration.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner.

Conductive film element precursors (identified Element 1 and Element 2)were prepared using a 125 μm poly(ethylene terephthalate) substrate thatwas coated with a non-color photosensitive silver halide emulsion(Emulsion 1) containing 98 mol % silver chloride and 2 mol % silveriodide. The emulsion grains had cubic morphology and an edge length 0.36μm, and it was hardened using BVSM[1,1′-(methylene(sulfonyl))bis-ethane] coated at 0.5 weight % of totalgelatin to be a part of Layer 2 below.

A first layer (Layer 1) was provided directly on the substrate for UVabsorption. The UV absorption at 365 nm increased to 1.7 optical densityunits. Layer 1 included 1500 mg/m² of gelatin and 300 mg/m² of TINUVIN328 UV absorbing dye.

A photosensitive silver halide emulsion layer (Layer 2), which includedEmulsion 1 was provided over Layer 1. For Element 1, the silver (Ag) togelatin weight ratio was kept constant at 2.33:1 (or at a volume ratioof about 0.297:1). For Element 2, the silver (Ag) to gelatin weightratio was kept constant at 2.45:1 (or at a volume ratio of about0.313:1).

Both Elements 1 and 2 further included a hydrophilic overcoat layer(Layer 3) over Layer 2, which Layer 3 included 488 mg/m² of gelatin, 6mg/m² of 0.6 μm insoluble polymeric matte particles, and conventionalcoating surfactants.

The conductive film element precursors of Element 1 were imagewiseexposed through a chromed design mask having a diamond-shaped gridpattern with corner-to-corner dimensions of 300 μm (vertical)×500 μm(horizontal). The grid lines on the mask were approximately 3 μm wide.The width of each channel was 4.8 mm. The length of each channel was 85mm. The exposure was made with UV radiation at a wavelength of 365 nm.

The imagewise exposed silver halide films were processed to reduce thesilver cations to silver metal and to form conductive film elementsusing the processing sequences shown below in TABLE I. The evaluationresults of the conductive film elements are also shown below in TABLE I.

TABLE I Processing Sequence and Results for Element 1 Temp. Time(seconds) Processing Processing (° C.) Example 1- Example 2- Example 3-Example 4- Example 5- Example 6- Step Solution All Trials InventionComparison Comparison Comparison Comparison Comparison First Developer1A 40 20 20 60 None None 20 Developing Washing Water 40 60 60 60 NoneNone 60 Second Developer 2A 40 180 None None 180 None None DevelopingDeveloper 2B 40 None None None None 180 180 Fixing Fixing solution 40 6060 60 60 60 60 Washing Water 40 60 60 60 60 60 60 Drying 60 600 600 600600 600 600 Relative Resistance 1.0 40 10 >300 1.5 0.6 Visual D_(min)0.024 0.023 0.025 0.023 0.086 0.072

The resistances of five identical channels described above, weremeasured using a two-point probe on contact pads located at the end ofeach conducting channel and the two-point probe is connected to anohmmeter. Visual D_(min) was measured in a non-exposed region of theconductive film elements using an X-Rite Model 310 densitometer. Visualdensity was a weighted average of red, green, and blue densitiesdesigned to simulate the sensitivity of the human eye. The relativeresistances and visual D_(min) values for the six trials are included inTABLE I to demonstrate the advantage of the present invention. Thecombination of Developer 1A and Developer 2A (Invention Example 1)provided both low resistance and low visual D_(min). Developer 1A alone(Comparison Examples 2 and 3) or Developer 2A alone (Comparison Example4) exhibited very high resistance. A conventional black and whitedeveloper, Developer 2B gave low resistance (Comparison Example 5), butvery high visual D_(min). Developer 1A used in combination with theconventional black and white developer, Developer 2B (Comparison Example6) also gave good resistance, but unacceptable visual D_(min).

The conductive film element precursors of Element 2 were exposed asdescribed above and then processed using the processing sequences shownbelow in TABLE II. The sheet resistances were obtained using two-pointprobe measurements that were made on a 1×1 inch (2.54 cm×2.54 cm) gridusing the contact pads in direct contact with that grid, yieldingresistances in units of ohms/square.

TABLE II Processing Sequence and Results for Element 2 Temp. Time(seconds) (° C.) Example 7- Example 8- Example 9- Example 10- ProcessingStep Solution All Trials Invention Invention Invention Comparison FirstDeveloper 1A 40 20 20 20 None Developing Developer 1B 40 None None None120 Washing Water 40 60 60 60 60 Second Developer 2A 40 180 None NoneNone Developing Developer 2C 40 None 180 None None Developer 2D noneNone None 180 None Fixing Fixing solution 40 60 60 60 60 Washing Water40 60 60 60 60 Drying 60 600 600 600 600 Sheet Resistance 73 290635 >100,000 Visual D_(min) 0.031 0.034 0.030 0.033

The sheet resistance values for the four trials are included in TABLE IIdemonstrate the advantage of the present invention. Combinations of thefirst developer and second developer used in the practice of the presentinvention (Invention Examples 7, 8, and 9) provided much lower sheetresistance compared to using a single conventional developer comprisedof ascorbic acid and N-methyl-p-aminophenol (Comparison Example 10).

The compositions of the processing solutions used in these Examples areshown in TABLES III through IX. All of these processing solutions wereaqueous solutions prepared using demineralized water.

TABLE III Developer 1A Components g/liter Potassium hydroxide, 45.5%solution 10.83 Sodium bromide 5.004,4-Dimethyl-1-phenyl-3-pyrazolidinone 0.33 1-Phenyl-5-mercaptotetrazole0.13 5-Methylbenzotriazole 0.17 50% solution of sodium hydroxide 1.82Phosphonic acid, (nitrilotris(methylene))- 0.29 tris-, pentasodium saltN,N′-1,2-Ethanediylbis(N-(carboxymethyl)- 1.77 glycine Sodium carbonatemonohydrate 8.33 Potassium sulfite, 45% solution 83.33 Hydroquinone12.50 5,5′-(dithiobis(4,1-phenyleneimino))bis(5- 0.12 oxo-pentanoic acidpH 10.55

TABLE IV Developer 1B Components g/liter Ascorbic acid 8.00 Sodiumcarbonate 17 N-Methyl-p-aminophenol 1.80 5-Methylbenzotriazole 0.16 pH10.10

TABLE V Developer 2A Components g/liter Sodium sulfite 92.54Hydroquinone 4.630 N,N-Bis(2-(bis(carboxymethyl)- 0.950 amino)ethyl)-Glycine, pentasodium salt Sodium tetraborate pentahydrate 2.830 Sodiumthiocyanates 0.42 pH 9.11

TABLE VI Developer 2B Components g/liter Sodium sulfite 92.54N-Methyl-p-aminophenol 1.85 Hydroquinone 4.63N,N-Bis(2-(bis(carboxymethyl)- 0.95 amino)ethyl)- Glycine, pentasodiumsalt Sodium tetraborate pentahydrate 2.83 Sodium thiocyanate 0.42 pH9.11

TABLE VII Developer 2C Components g/liter Ascorbic acid 8.00 Sodiumcarbonate 17 Diethylenetriamine pentaacetic acid, 7.56 pentasodium saltpH 10.10

TABLE VIII Developer 2D Components g/liter Ascorbic acid 8.00 Sodiumcarbonate 17 Sodium sulfite 12 Potassium thiocyanate 0.10 5-Phenylmercaptotetrazole 0.15 pH 10.10

TABLE IX Fixing Solution Components g/liter Acetic acid 24.43 Sodiumhydroxide, 50% solution 10.25 Ammonium thiosulfite 246.50 Sodiummetabisulfite 15.88 Sodium tetraborate pentahydrate 11.18 Aluminumsulfate, 18.5% solution 36.26 pH 4.30

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

1. A silver halide solution physical developing solution comprising: (a)a primary developing agent that is a hydroquinone or ascorbic acid orderivative of either, in an amount of at least 0.01 mol/l and up to andincluding 1 mol/l, and (c) a silver halide dissolution catalyst in anamount of at least 0.001 mol/l and up to and including 0.1 mol/l, andthe silver halide solution physical developing solution containingsubstantially no (b) catalytic developing agent.
 2. The silver halidesolution physical developing solution of claim 1, further comprising analkali metal sulfite in an amount of at least 0.2 mol/l and up to andincluding 3 mol/l.
 3. The silver halide solution physical developingsolution of claim 1, further comprising sodium sulfite or potassiumsulfite in an amount at least 0.5 mol/l and up to and including 1 mol/l.4. The silver halide solution physical developing solution of claim 1,wherein the silver halide dissolution catalyst is an alkali metalthiocyanate in an amount of at least 0.005 mol/l and up to and including0.05 mol/l.
 5. The silver halide physical developing solution of claim 1further comprising one or more metal ion complexing agents in a totalamount of at least 0.001 mol/l.
 6. The silver halide physical developingsolution of claim 5 further comprising a calcium or silver metal ioncomplexing agent as a metal ion complexing agent in a total amount of atleast 0.001 mol/l.
 7. The silver halide physical developing solution ofclaim 1 having a pH of at least 8 and up to and including
 12. 8. Thesilver halide physical developing solution of claim 1, wherein theprimary developing agent is hydroquinone or a derivative thereof, andthe silver halide dissolution catalyst is sodium thiocyanate orpotassium thiocyanate.
 9. The silver halide physical developing solutionof claim 8, further comprising a sodium sulfite or potassium sulfite inan amount of at least 0.5 mol/l and up to and including 1 mol/l.
 10. Thesilver halide physical developing solution of claim 1 that isconcentrated at least 4 times compared to a desired working strengthconcentration.